Fractional distillation process and apparatus



P 1952 K. c. D. HICKMAN 2,609,335

FRACTIONAL DISTILLATION PROCESS AND APPARATUS Filed May 2, 1944 2 SHEETS'-SHEET 1 1 16.21 FIG.1. 20

: 12-{ 22 9 24 w I v KENNETH. C.D. HICIMAN INVENTOR A TTORNEYS Sept. 2, 1952 K. c. D. HICKMAN FRACTIONAL DISTILLATION PROCESS AND APPARATUS 2 SHEETSSHEET 2 Filed May 2, 1944 FIG.

FIG.3.

KENNETH C.D.HICKM4N INVENTOR BY WV ATTORNEYS Patented Sept. 2, 1952 FRACTIONAL DISTILLATIONPROCESS AND" ;J""f-APPARATUS .Kniiethiiol'pi' nickman, Rochester, N. Y., 3. Q sig'iionii byi' ime'sn'e i'assignmenta 'to I. Eastman j Kodakflompany, Rochester, NLY; a corporaiqn i 'li wtJ rsex instants-May 2,1944, Serial No. states q 1 a min This invention relates proeessand apparatus for ieh' f n ands reminis e-1 s- .Q'. .w'l'.

-It has been appreciatedpreviously-thatordinary rectifying columns gontaining p ubble caps,

fractionating packing; etc., were unsuitable for vacuum fractionation. This is due to the fact that the packing or bubble caps offer great re sistance to -the flow oi vaporsso; that pressure was built up in l umn or l l is;.:i a n pile-.- bsi tu t to the flow of vapors to be tractionated have been i used forvacuum fractionation; Howeyensuch widely spaced platesofiering constructions have; not beenfsatisfactory. The vapors pass through thecolumnQwitha high velocity so that e fficlent interchange betwen reflux a v p sim o sihh-J Alsa. opl s.-

condensate are carried along with the-high velocity vapors and contaminate the:fractions re movedinthecondensen; "j

This invention has for itsobject ;to overcome the above difliculties. vide .improved vacuum fractionating process and apparatus. Another object is to provide improved vacuum process and apparatus permitting efficient interchange betwen vapors and condensate without causing pressure drop. Other objects will appear hereinafter.

These and other objects are accomplished by my invention which includes vacuum fractionating process and apparatus wherein the vapors to be fractionated are caused to pass between opposite surfaces'one of which is cooled and the other of which is heated, said surfaces being spaced from each other to permit the vapors to flow therebetween, and conveying at least part of the condensate condensed on the cooled sur face onto the opposite heated surface.

My invention is typified by what may be termed the cooled-stirrer, hot-wall" still. The general construction of such a still may include a pot or flash boiler which communicates with a wide substantially vertical vapor fractionating column, this in turn communicating with. a condenser. The walls of the vapor column-are supplied with heat in'a controlledpmanner. Within this as-' sembly there is-a long stirring member, the lowest portion of which preferably dips into the distilland, producing violent agitation; The cen-' tral portion of the stirrer; namely,- that which is within the vapor column; is hollow and is-supplied with a cooling fluid-air, water, oil, etc. During the operationof the still, vapor generated in the pot attempts .to. .ascendithe column'andflis partially or wholly condensed on the rotatin Another object is topro- (Cl. 2024.0) A ,2 m r-1Tb? ec qe s i ms e mfi l force-from thernelnb ;th heated"walls"fof thevapor column; Here. artial refvaporation cursw i t a o oni' s n Miam 5 moment re -evaporated falls f downwards ftoward -r t iv p atf q; H ha-swim t er hand, passes upwards anditowards the Tcenter.

As a net result there are many condeasaaoiisfl and re-evaporations the heavi awa s tending to pass down the c lumn, the lig-h e'rconstituents tending to" pass up.' A fractionationex ing to many plates-is achieved. 1

ceeding one heoretical; plate and' o' fteri amount V Superimmse 101L131? i mli t retrace, onsaea o eas e a i e: n r han e tw n vaporandlligiiiq as the rane spc tlebs T nsate. a e l i 1 a 1y l a t cooled stirrer to the hot walls. "I- consider as h n th rsq e fnir inve t on th wi tion of the cooled stirrerand heat wall with all known meansiqjf spreading} therefi ux an d in in ai ntq niithfiixQfihifi'l iiifl ii i dies. a or -Z @u l w. a e he eq e shaft rin er-h ss rm @1 9: t i s ai s. Wir s aedptl 9 95 seaq eh t e on shaitain atu tb .i a h -Qi.-Yw Spread the reflux; and at the same time to pre'servea :'re terenwerk i uet ii .1 1. h fellow QmP F. a A m e I have 'mseveral of the preierred embodiments of m .m eii it uti s.= @:i i i 0 d t t these are-set forth for th e purpose lot illustration; and n 1111- l mi ai s nz cr ef In theqs m ym dr s f numbers refer taiigg a ll 3W6; illustrated er l emboq i se sofim -ns r i tr'hi t fi Fig: l is an: elevation partly in sectionofeaiihs s i l rbj c iiv 'i 'l a'n and .rotatable internally cooled I n s ior conhS aaa re r in se s: 11 615116 siteheated walll i W fluid rom. t e: ,c'oo an a d We lan c.

iss' sane e tionr 1 n actio o a still mbody he: f tures; Q lFi lstationary'means ifor greturning 000 c totheo osite.heatedwall Referring to Fig. 1, numeral 6 designates an apparatus casing provided with a gas tight but removable cap 8 which is integral with a conduit It connected to vacuum pumps (not shown). Numeral I2 indicates a hollow shaft rigidly held in a central position in casing 6 by bearing Id and packed gland I6. Numeral I8 designates a pulley which serves to drive shaft I2. Numeral 20 designates a stationary conduit for introducing cooling fluid into the central portion of shaft I2. integral with the inside wall of casing 6 and numeral 24 a withdrawal conduit for removing liquid from gutter 22.

Shaft I2 carries a spiral-shaped member 23 and conical member 28 which are integral therewith and which rotate during rotation of shaft I2. Casing 6 is provided with a jacket 32 made of insulating material and with an electrical heating coil embedded in the insulating material as illustrated.

Referring to Fig. 2, numeral 34 designates a cylinder which is positioned inside casing 6 and approximately concentric therewith so that there is a space 36 therebetween. Numeral 38 designates perforations in tube 20 so as to permit cooling fluid to beejected against the walls of shaft I2 at desired points. Numeral 69 designates a gas burner for heating the lower portion of the apparatus.

Referring to Fig. 3, numeral 42 designates a e centrally positioned shaft carried by bearing hi and packed gland I6 which is analogous to hollow shaft l2 except that it is uncooled. Shaft i2 carries a series of spaced circular plates 46.

Numeral 46 designates a plurality of cooling coils which isclo'sed at the lower end by cap 54. Upon shaft 52 is mounted a stationary spiral 56 which is spaced from the wallof casing 6 by lugs 53.

In operating the apparatus illustrated in Fig. 1, cap 8 is removed and liquid to be distilled indicated by numeral I I is introduced into the apparatus. The electrical heating element 32 is put into operation and the equipment is evacuated by way of conduit I0. Force is applied to pulley I8 to cause the shaft I2 and spiral element 26 to rotate. Liquid to be distilled is continuously stirred and circulated by rotation of the conical element 28, the liquid traveling upward due to centrifugal force spilling over the upper lip of the cone in the manner indicated by the arrows. When this liquid has reached distillation temperature the vapors pass upward between the walls of 6 and the cool surfaces I2 and 26. The vapors instead of passing upwardly with high velocity, are condensed at intermediate points on the element 26 or on shaft I2. The condensate is" thrown by centrifugal force onto the opposite wall 6, down which it flows in a thin film. This condensate is, therefore, reheated on wall 6 to distillation temperature. These vapors thus generated on wall 6 again pass upward and become partially recondensed on the Numeral 22 designates an annular gutter nection with Fig. 1.

spiral 26 of Fig. l.

drawn through conduit 24. Since the vapor stream is thus repeatedly cooled and reheated, it is continually deflected from its upward course and is thus prevented from passing through the equipment with high velocity and without fractionation.

The operation of the apparatus illustrated in Fig. 2 is much the same as that described in con- However, the vapors are condensed on the plates 21 instead of on the The effect of the plates in 21 is much the same as the spiral. The holes 38 in the central tube 20 permit the cooling fluid introduced through'conduit 20 to be applied at any desired portion of the cooling surface I2. Thus, in Fig. 1 thecooling fluid was introduced only at the end of the conduit 20 so that it was .heated to a certainextent by the time it reached the upper portion of conduit I2. However, the modification shown in Fig. 2 permits the cooling fluid to be applied at any desired point or points on conduit l2. It is evident that by controlling the amount of cooling fluid the'proportion of the ascending vapors condensed on the shaft I2, and the proportion of condensate obtained in any particular section of the apparatus can be controlled. The vapors also pass upward in the space 36 between conduit 34 and easing 6. These vapors serve to warm the wall 34 so that external heating as illustrated in Fig. 1 is unnecessary. The liquid flung'from the discs 2'! onto the wall 34 is revaporized by the latent heat given up by the vapors in space 36. This evaporation is possible because the pressure will in general be less at the top of theapparatus than it is in the bottom or vaporizing section of the apparatus. This arrangementmakes a self-compensating still which would perform under a wide variation of the supply of cooling fluid to the central shaft l2. Fractionated vapors condensed on the top air-cooled wall of casingfi flow downward into gutter 22 and are withdrawn through conduit 24.

In operating the apparatus illustrated in Fig. 3, the still isheated and'eva'cuated as described with Fig. 1. Shaft 42 and plates is are rotated as a unit and cooling fluid is introduced through conduit 48 and withdrawn through 59. Vapors passing upward are partially condensed on cooling coils 5. The condensate drips from the lower portion of these coils onto disc 24 immevapors pass upward.

diately below. This liquid is then thrown by centrifugal force onto the opposite wall of casing 6. The repeated condensation and evaporation described above thus takes place as the remain stationary. These elements. however, be-

come cooled and vapors in their passage upward through the apparatus become condensed thereon. The liquid condensate flows by gravity toward the periphery of the spiral 56 and flows thence onto'the 1ugs 58- and onto the wall of surfaces I2 and 26. There is thus a plurality of condensations and re-evaporations during the passage of the vapors through the column. Vapors which have been repeatedly refractionated are condensed on the upper part of the wall 6 by the cooling' coils designated by the numeral 9. The condensate collects in gutter 22 and is withcasing 6 where they are at least partially revaporized. There is thus a downward flow of condensate along the walls'of casing 6, an upward flow of vapors, and repeated condensation and re-evap'oration as described above. Agitating cup 28 is rotated by extending shaft I6 through a gas tight bearing in the base of the apparatus.

Many modifications'may be made in my inventionwithout departing from the spirit or scope thereof.- f-l hus, I have found it convenient to illustrate equipmentproviding vaporizing means integral with the fractionating column. However, if desired, the material to be fractionated can-be vaporized in a separate vaporizing means and introduced into the fractionating column,

Also, the stirring means illustrated to assist in vaporizing the liquid to be distilled can be eliminated although this is not recommended. The

amount of cooling applied to the cooled surface can be varied in order tocontroltheamountof condensate and the number of condensations and re-evaporations. This, of course, willcontrol the amount of residue or refluxuipwing down the wall of the column, as =well-.as the amount of vapors condensed and removed asa fraction from the top of the column. Itis apparent'that imstead of discs, plates or helices, onemay use wires, bristles, brushes, paddles or other means to convey and to distribute the liquid on the opposite heated surface. While I prefer cylindrieal equipmerit because of its ease of construction, flat surfaces or any other desired shape may be employed, Likewise,if desired, the fractionated vapors need not befcondensedin the column itself but may be ledbff through awideapertureconduit to a suitableoondenser. What I claim is:

1. A fractio nal distillation apparatus;compris- 2. Afractional distillation apparatus compris ing a vertical tubular member having a uniform cross section, condensing means centrally positioned' within said tubular member and distributed over the major 'portion'of the length of said tubular member, means within said tubular member for centrifugally' throwing condensate from said condensing means onto the inner surface of said tubular memberat a plurality of axially spaced positions' and means for heating said tubular member to a temperature sufficient to at least partially re-evaporate said condensate.

v3. A fractional distillation apparatus comprising a vertical tubular member having a uniform cross section condensing means centrally positioned within said tubular member and distributed over the major portion ofthe length of said" first named tubular member, and means for heating said first named tubular member to a temperature sufiicient to at least partially re-evaporate said condensate.

4. A fractional distillation apparatus comprising a stationary vaporizing surface and a condensing surface arranged in spaced apart relation and defining therebetween a confined and u wa r ir c d p sae wayfor vapors; means? for coolingsaid-condensing surface,- centrifugal conveying means disposed longitudinally within said passageway and arranged for moving condensate -;across said passageway "from said condensing surface and distributing it onto said vaporizing surfaceat a pluralitypfpositions along said passageway, meansjfor heating said vaporizingfsurface.to:-a,temperature sufficient to at 10 least partially re-evaporate said condensate,

' meansadiacent-the upper end of said passageway for;v totally condensing: vapors reaching the uppenepd. of, said passageway, and means for collecting;productjrom said total condensing lamea am Afra-ctional distillation apparatus comprising-a-;generally vertical tubular member, condensing "means centrally positioned within said tubular member and-distributed over a substango tial portionv of the length of said tubular member, means for introducing vapors to be fractionated 'into a lower, zone of said tubular member, rotatable means'withinsaid tubular member for centrifugally throwing condensate from said condensing means onto the inner surface of said tubular member ata multiplicity. of axially spaced positions, :means for heating said tubulartmember to; a, temperature sufficient, to. at. least partially"; re-evaporate said condensate, .means for s evacuating said tubular member, and means for condensing and collecting :vapors in an upper zoneof said tubularmember.

6; A fractional distillation apparatus comprising; vapor generating means; opposed generally vertical-vaporizing and'condensing surfaces defining f therebetween a confined passageway of substantially uniform cross section', the lower end of saidtipassagewaycommunicating with said vapor-generating means,'1meanslfor evacuating said 4o passagewammeans adjacent the upper end of condensing surface, means for centrifugally throwing condensate across said'passageway from I saidcondensing surface onto said vaporizing surfaceiat aplurality of'spaced positions along said passageway, and means for heating said vaporizing surface to a temperature suificient to at least partially reeevaporate' said condensate.

7.-. ,A fractional distillation apparatuscomprising vapor generating means, a generally tubular member of substantially uniform cross-section communicating with said vapor generating means and extending, generally vertically upward from said vapor generating means, condensing means centrally positioned within said tubular member and extending through a substantial portion of the length of, said tubular member, said'Conidensing means comprising a rotatable tubular member arranged in substantially coaxial rela tion with said first-named tubular member, means for circulating cooling fluid within said rotatable tubular member, means for rotating said rotatable first-named tubular member to a temperature suificient to at least partially re-evaporate said condensate, means for evacuating the space between said first-named tubular member and said rotatable tubular member, and means adjacent the upper end of said first-named tubular mem- 7 her for totally condensing and collecting vapors reaching an upper zone of said first-named tubular member. v

8. A fractional distillation apparatus comprising an outer tubular member having a lower vaporizing zone and an upper condensing zone, an annular gutter mounted around the lower margin of said condensing zone and being arranged for collecting condensate from said condensing zone, means for withdrawing condensate from said gutter, an inner tubular member generally concentric with said outer tubular member and extending throughout a substantial portion of the length of said vaporizing zone of said outer tubular member, means for cooling said inner tubular member, means for conveying condensate portions from said inner tubular member and distributing them onto said vaporizing zone of said outer tubular member at a multiplicityv of levels, and means for heating said vaporizing zone of said outer tubular member to a temperature sufi'icientto at least partially reevaporate said condensate portions.

9. A fractional distillation apparatus comprising spaced apart opposed surfaces defining therebetween an upwardly directed confined passageway forvapors, the first of said surfaceshaving a lower vaporizing zone and an'upper total'condensing zone, means for collecting product from said total condensing zone, means for cooling the second of said surfaces, 'means disposed along said passageway for conveying condensate across said passageway from said second surface and for distributing it on the vaporizing zone of said'first surface at spaced positions along said passageway, and means for heating said vaporizing zone of said first surface to a temperature sufficient to at least partially re-evaporate said condensate, said first surface being constructed and arranged for downward flow of condensate over said surface during operation of said apparatus 10. A fractional distillation apparatus comprising a lower vapor-generating portion, an intermediate fractionating portion, an upper total condensing portion, and gutter means arranged for collecting product from said total condensing portion, said intermediate fractionating portion comprising a vaporizing surface and a condensing surface defining therebetween a confined and upwardly directed passageway for vapors, means for cooling said condensing surface, centrifugal conveying means disposed along said passageway and arranged for moving condensate across said passageway from said condensing surface and onto said vaporizing surface, and means for heating said vaporizing surface to a temperature suf-' ficient to at least partially re-evaporate said condensate, said vaporizing surface being constructed and arranged for downward flow of unvaporized residue oversaid vaporizing surface.

11. The process which comprises passing an annular stream of vapors along an upwardly directed path between concentric surfaces, condensing portions of said vapors out of said stream onto one of said surfaces, centrifugally conveying the resulting condensate portions across said stream of vapors onto the other of said surfaces. partially revaporizing said condensate portions from said last-named surface back into said stream of vapors, flowing the unvaporized residue of said condensate portions downwardly over said last-named surface in the form of a thin film, repeating said condensing and revaporizing at successively higher levels along said path, totally condensing said vapors in an upper zone along said path, and collecting and withdrawing prodnot from said upper zone.

12. The process which comprises passing a stream of-vapors upwardly through an annular space between generally concentric tubular members, cooling the inner tubular member, heating the outer tubular member, and, during passage of said vapors upwardly through said space, progressively fractionating said vapors at a multiplicity'of successively higher levels by repeatedly condensing portions of said vapors upon said inner tubular member, rotating said inner tubular member at a speed effective to centrifugally throw the resulting condensate portions across said space onto said outer tubular member, partially revaporizing said condensate portions from said outer tubular member back into the upfiowing vapor stream and causing the unvaporized residue of said condensate portions to flow downwardly along said outer tubular member.

' KENNETH C. D. HICKMAN.

REFERENCES CITED The following references are of record in the V file of this patent:

" UNITED STATES PATENTS 7 OTHER REFERENCES Industrial and Engineering Chemistry, Analytical Edition, vol. 10, page 450 (1938), vol. 12, pages 468-471 (1940). (Copies in Scientific Library.) 

11. THE PROCESS WHICH COMPRISES PASSING AN ANNULAR STREAM OF VAPORS ALONG AN UPWARDLY DIRECTED PATH BETWEEN CONCENTRIC SURFACES, CONDENSING PORTIONS OF SAID VAPORS OUT OF SAID STREAM INTO ONE OF SAID SURFACES, CENTRIFUGALLY CONVEYING THE RESULTING CONDENSATE PORTIONS ACROSS SAID STREAM OF VAPORS ONTO THE OTHER OF SAID SURFACES, PARTIALLY REVAPORIZING SAID CONDENSATE PORTIONS FROM SAID LAST-NAMED SURFACE BACK INTO SAID STREAM OF VAPORS, FLOWING THE UNVAPORIZED RESIDUE OF SAID CONDENSATE PORTIONS DOWNWARDLY OVER SAID LAST-NAME SURFACE IN THE FORM OF A THIN FILM, REPEATING SAID CONDENSING AND REVAPORIZING AT SUCCESSIVELY HIGHER LEVELS ALONG SAID PATH, TOTALLY CONDENSING SAID VAPORS IN AN UPPER ZONE ALONG SAID PATH, AND COLLECTING AND WITHDRAWING PRODUCT FROM SAID UPPER ZONE. 